Large bellows that are used to protect a moveable connection such as on an articulating vehicle typically have a pleated type construction manufactured from many pieces of coated fabric that are sewn together and supported by perimeter frames. In some constructions the perimeter frames may be located at the outer perimeter of the fabric pleats. In other constructions, the perimeter frames may be located along the inner perimeter of the fabric pleats. In constructions where the frames are located at the outer perimeter, the fabric pleats are typically made of separate fabric pieces that are stitched together to form the folds of the pleat, resulting in a “V” shaped cross-section, referred to as a folding construction. In another construction having the frames located at the outer perimeter, the fabric is allowed to remain as a flat piece, which results in a “U” shaped cross-section. This alternate method of construction is often referred to as a corrugated construction. Due to the “U” shape of these bellows, separate fabric pieces are used to create the pleated shape. Like the previously described construction, the fabric pieces are joined together on the edges by the perimeter frames or by stitching.
Assembly of typical articulating vehicle bellows is a labor intensive process that requires the handling of numerous individual fabric panels, alignment of inner and outer edges of each of the fabric panels, and then stitching the panels together or crimping the aluminum support frames to the fabric panels to create the final configuration. As shown in FIGS. 1-3, typical folding type bus bellows 10 require fourteen individual panels per section, with ten sections, or 140 individual panels per assembled bellows. Typical corrugated bellows will require seventeen individual panels per section, with ten sections, or 170 individual panels per assembled bellows.
Additionally, as shown in FIG. 3, perimeter frames 20 used in typical articulating vehicle bellows 10 must be very large because they are formed to the entire perimeter shape. Such large perimeter frames 20 require that the bellows 10 be assembled one folding, or corrugated section, at a time with each section having a perimeter frame 20 and a fabric section 22 made from the many individual panels.
An additional drawback to traditional articulating vehicle bellows is that a significant amount of stitching is required to join the individual fabric pieces together as well as to join the assembled fabric pieces to one another in creating individual folding sections. A typical bellows having the multitude of fabric panels described above requires over 2,500 inches of stitching to create the folding sections. Every inch of the stitching also requires manual sealing in order to prevent liquid or air from penetrating the seams. The sealing of the seams is commonly accomplished by using an adhesive or caulk type sealer, and is typically a manual process.
As shown in FIGS. 1B and 1C, typical folding bellows 10 also require that the corner fabric pieces 24, 26 be individual panels with rounded shaped corners to transition from a horizontal side to a vertical side. The individual corner fabric pieces 24, 26 which are used to create the radius corner result in a large amount of material scrap due to their shape and inability to be nested closely in a CNC fabric cutting program. Additionally, the radius corners are subject to a large amount of stress because they must be tight enough to provide support to the bellows 10 in the standard mounted position and to prevent excessive sagging of the bellows, but also allow the folds to open enough so that the bellows can make a large extension when an articulating vehicle turns. This requires the corner pieces and corner stitching to be stretched tightly during the turn.
There have been efforts to use a folding corner in some cases to replace the rounded corners of the bus bellows. In one case, a tongue-in-groove type folding arrangement is used to transition the pleats from a horizontal side to a vertical side. This folding arrangement has drawbacks due to the significant flexing stress placed on the fabric material which leads to premature flex fatigue failure of the fabric which results in a hole in the fabric, and thus, an inability of the bellows to prevent air and liquid from intrusion into the area to be protected.
Another common folding arrangement has a chamfered or mitered corner. This folding arrangement allows the fabric material to roll, rather than crease which results in less flex fatigue placed on the fabric. Both of the folding arrangements previously described have been common to the manufacture of standard folding bellows for a very long time. Both folding arrangements can also allow for a larger opening of a corner than the rounded shaped corner allows for and thus make it possible to reduce the number of folds.
Accordingly, there is a need for a bellows design that allows for a less complex and expensive method of manufacture by using fewer fabric panels, less material, and requiring less, and easier, handling of the fabric and support frames. There is also a need for a bellows that does not require manual sealing of the stitching holes that are created in a typical folding type articulating vehicle bellows.